ui: Hide slice implementation details from subclasses
For performance we want to stash some data for each slice
that is only relevant to the base class (specifically 'x'
the pixel offset and 'w' the pixel width of the slice).
This change uses some type magic to hide these properties from
subclasses to avoid that people start depending on them.
Bug: 207474444
Change-Id: I4022d5031067f5122500c6d3de0fdbb001b7ad60
diff --git a/ui/src/frontend/base_slice_track.ts b/ui/src/frontend/base_slice_track.ts
index dc818d3..55eed50 100644
--- a/ui/src/frontend/base_slice_track.ts
+++ b/ui/src/frontend/base_slice_track.ts
@@ -57,6 +57,21 @@
export type BaseSliceRow = typeof BASE_SLICE_ROW;
+// These properties change @ 60FPS and shouldn't be touched by the subclass.
+// since the Impl doesn't see every frame attempting to reason on them in a
+// subclass will run in to issues.
+interface SliceInternal {
+ x: number;
+ w: number;
+}
+
+// We use this to avoid exposing subclasses to the properties that live on
+// SliceInternal. Within BaseSliceTrack the underlying storage and private
+// methods use CastInternal<T['slice']> (i.e. whatever the subclass requests
+// plus our implementation fields) but when we call 'virtual' methods that
+// the subclass should implement we use just T['slice'] hiding x & w.
+type CastInternal<S extends Slice> = S&SliceInternal;
+
// The meta-type which describes the types used to extend the BaseSliceTrack.
// Derived classes can extend this interface to override these types if needed.
export interface BaseSliceTrackTypes {
@@ -69,7 +84,7 @@
BaseSliceTrackTypes> extends
Track<T['config']> {
// This is the slice cache.
- private slices = new Array<T['slice']>();
+ private slices = new Array<CastInternal<T['slice']>>();
protected sliceLayout: SliceLayout = {...DEFAULT_SLICE_LAYOUT};
// These are the over-skirted cached bounds.
@@ -199,7 +214,7 @@
// Filter only the visible slices. |this.slices| will have more slices than
// needed because maybeRequestData() over-fetches to handle small pan/zooms.
// We don't want to waste time drawing slices that are off screen.
- const vizSlices = this.getVisibleSlices(vizTime.start, vizTime.end);
+ const vizSlices = this.getVisibleSlicesInternal(vizTime.start, vizTime.end);
let selection = globals.state.currentSelection;
@@ -217,7 +232,7 @@
const rowSpacing = this.computedRowSpacing;
// First pass: compute geometry of slices.
- let selSlice: T['slice']|undefined;
+ let selSlice: CastInternal<T['slice']>|undefined;
// pxEnd is the last visible pixel in the visible viewport. Drawing
// anything < 0 or > pxEnd doesn't produce any visible effect as it goes
@@ -451,7 +466,7 @@
// abstract call.
convertQueryResultToSlices(
queryRes: QueryResult, startNs: number, endNs: number, bucketNs: number) {
- const slices = new Array<T['slice']>(queryRes.numRows());
+ const slices = new Array<CastInternal<T['slice']>>(queryRes.numRows());
const it = queryRes.iter(this.getRowSpec());
let maxDataDepth = this.maxDataDepth;
@@ -463,12 +478,19 @@
// Construct the base slice. The Impl will construct and return the full
// derived T["slice"] (e.g. CpuSlice) in the rowToSlice() method.
- slices[i] = this.rowToSlice(it);
+ slices[i] = this.rowToSliceInternal(it);
}
this.maxDataDepth = maxDataDepth;
this.slices = slices;
}
+ private rowToSliceInternal(row: T['row']): CastInternal<T['slice']> {
+ const slice = this.rowToSlice(row) as CastInternal<T['slice']>;
+ slice.x = -1;
+ slice.w = -1;
+ return slice;
+ }
+
rowToSlice(row: T['row']): T['slice'] {
const startNsQ = row.tsq;
const startNs = row.ts;
@@ -500,8 +522,6 @@
// them to something.
baseColor: DEFAULT_SLICE_COLOR,
color: DEFAULT_SLICE_COLOR,
- x: -1,
- w: -1,
};
}
@@ -568,7 +588,13 @@
return true;
}
- getVisibleSlices(startS: number, endS: number): Array<T['slice']> {
+ private getVisibleSlicesInternal(startS: number, endS: number):
+ Array<CastInternal<T['slice']>> {
+ return this.getVisibleSlices(startS, endS);
+ }
+
+ getVisibleSlices(startS: number, endS: number):
+ Array<CastInternal<T['slice']>> {
let startIdx = -1;
let endIdx = -1;
let i = 0;
diff --git a/ui/src/frontend/slice.ts b/ui/src/frontend/slice.ts
index ddbbb98..5b660ef 100644
--- a/ui/src/frontend/slice.ts
+++ b/ui/src/frontend/slice.ts
@@ -28,13 +28,4 @@
subTitle: string;
baseColor: Color;
color: Color;
-
- // These properties change @ 60FPS and shouldn't be touched by the Impl.
- // to the Impl. These are really ephemeral and change on every frame. But
- // the Impl doesn't see every frame. Somebody might be tempted to reason on
- // those but then fail.
- // TODO(hjd): Would be nice to find some clever typing hack to avoid exposing
- // these.
- x: number;
- w: number;
}